That's a tricky question! It depends on what you mean by "covered."

* Venus: This planet is completely enveloped in thick, dense clouds of sulfuric acid. These clouds are so thick, they block almost all sunlight from reaching the surface.

* Jupiter, Saturn, Uranus, and Neptune: These gas giants all have thick layers of clouds composed of various gases like ammonia, methane, and water. These clouds are constantly changing and swirling, creating spectacular storms.

* Earth: While Earth has a relatively thin layer of clouds, it is important for our climate and weather.

So, which planet is "covered" depends on how you define it.